GB2222913A - Electromagnetic-shielding gasket or sealing member - Google Patents

Electromagnetic-shielding gasket or sealing member Download PDF

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Publication number
GB2222913A
GB2222913A GB8921115A GB8921115A GB2222913A GB 2222913 A GB2222913 A GB 2222913A GB 8921115 A GB8921115 A GB 8921115A GB 8921115 A GB8921115 A GB 8921115A GB 2222913 A GB2222913 A GB 2222913A
Authority
GB
Grant status
Application
Patent type
Prior art keywords
gasket
electromagnetic
shielding
housing
electronic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8921115A
Other versions
GB8921115D0 (en )
GB2222913B (en )
Inventor
Hiroji Kitagawa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kitagawa Industries Co Ltd
Original Assignee
Kitagawa Industries Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00Screening of apparatus or components against electric or magnetic fields
    • H05K9/0007Casings
    • H05K9/0015Gaskets or seals

Description

F - r! 1 2 2z_ 29 '1 'o ELECTROMAGNETIC-SHIELDING GASKET OR SEALING

MEMBER This invention relates to an electromagneticshielding gasket or sealing member for sealing gaps and for preventing electromagnetic waves passing through the gaps for protecting electronic components from electromagnetic waves, and to a housing for electronic components provided with such a gasket or sealing member.

These days, office equipment, such as electronic typewriters and printers, household appliances, such as washing machines and vacuum cleaners, and the like increasingly use electronic components such as microcomputers or microprocessors. Even automobiles is equipped with electronic control systems for controlling fuel injection are increasing rapidly. Thus, the use of ters and microprocessors is increasing.

microcomput Moreover, the clock frequency of microcomputersand microprocessors is also increasing. Electronic components tend to generate a lot of electromagnetic radiation and noise. This radiation and noise can pass through gaps present in the housing in which the electronic components are housed, and may be transmitted to other electronic components, thus causing malfunctioning of or damage to the other electronic components. Many electronic components use magnetic recording elements manufactured by magnetising a highdensity magnetic substance using small magnetic energy. Data recorded in these elements can be easily distorted by stray magnetic fields.

In the related art, gaps in the housing of the electronic components are sealed by an electromagneticshielding gasket or seal consisting of a conductive metal (referred to as "the metallic gasket") or an electromagnetic-shielding gasket consisting of an elastomer containing carbon black (referred to as "the 1 1 2 elastomer gasket") to prevent electromagnetic waves from passing to the electronic components.

However, neither the %etallic gasket" nor the elastomer gasket" sufficiently shield the electronic components from electromagnetic waves, and each has problems.

The housing for the electronic components must be airtight or watertight depending on the environment in which the electronic components operate. For example, the location where a washing machine is operated is very humid. Where automobiles operate, various different environments are possible. Thus airtightness and watertightness are required for the electronic-component housing for washing machines and automobiles. The electromagnetic-shielding gasket or seal- must have conductivity or low electrical resistivity to shield the electronic components from electromagnetic radiation and noise. The electromagnetic-shielding gasket or seal must also be elastic so that the gasket can seal any gap in the housing to make the housing airtight or watertight. However. the related-art %etallic gasket" cannot resiliently deform or completely seal the housing.

On the other hand, the related-art "elastomer gasket" has high conductivity because the gasket contains conductive metallic particles or carbon black (referred to as "conductive particles"). The gasket also has elasticity because its base material is an elastomer. When the content of conductive particles is increased, the electrical resistivity is reduced. However, when the content of conductive particles exceeds a fixed amount, the elasticity of the base material deteriorates. Consequently, the content of conductive particles has an upper limit. However, even at that upper limit, the "elastomer gasket" cannot sufficiently shield the housing from electromagnetic 3 radiation and noise.

According to the present invention there is provided an electromagneticshielding gasket or sealing member for sealing gaps and for preventing electromagnetic waves from passing through the gaps, comprising a gasket or seal body formed of a synthetic elastomeric resin material, and a conductive membrane applied by an evaporation process onto a surface of the gasket or seal body.

The electromagnetic-shielding gasket or seal seals gaps that remain after several members are connected, and prevents electromagnetic waves from passing through the gaps.

Some embodiments of the present invention will now be described, by way of examples, with reference to the accompanying drawings, in which:- Figure 1 is a partially sectioned perspective view of a housing for electronic components provided with a first embodiment of a gasket embodying the present invention; Figure 2 is a sectional perspective view of the electromagnetic-shielding gasket shown in Figure 1; Figure 3 is a sectional perspective view of a second embodiment of an electromagnetic-shielding gasket embodying the present invention; Figure 4 is a sectional perspective view of a third embodiment of an electromagnet ic-shielding gasket embodying the present invention; Figure 5 is a sectional perspective view of a fourth embodiment of an electromagnetic-shielding gasket embodying the present invention; Figure 6 is a sectional perspective view of a fifth embodiment of an electromagnetic- shielding gasket embodying the present invention; and Figure 7 is a sectional perspective view of a 4 sixth embodiment of an electromagnet ic- shielding gasket embodying the present invention.

An electromagnetic- shielding gasket 1 is applied to the rim of a housing 3 that is provided with a movable lid 5. Embodiments of the electromagneticshielding gasket are explained with reference to the drawings.

In Figure 1, an electromagnetic-shielding gasket 1 which constitutes a first embodiment of the present invention is attached to a box-like housing 3 that houses electronic components. The housing 3, which is metallic, has an opening 4 for housing electronic components. A metallic lid 5 is pivotably connected by hinges 7 to the housing 3 so as to be able to close the is opening 4.

The electromagnetic-shielding gasket 1 is attached by means of a conductive adhesive to a rim 9 that abuts the lid 5 when the lid 5 is closed. The housing 3 and the lid 5 have fasteners 11 to cause the lid 5 to be held tightly in contact with the electromagneticshielding gasket 1 when the lid 5 closes the housing, 3, thus sealing the electronic components in the housing 3. An electrical conductor (not shown) for the electronic components in the housing 3 passes through a waterproof connector 13 in the side wall of the housing 3.

As shown in Figure 2, the electromagneticshielding gasket 1 has a rectangular section. An aluminium layer 17 of about four microns thick is applied by an evaporation process onto the surface of a gasket body 15 consisting of silicone rubber. An embodiment of the electromagneticshielding gasket 1 has the following physical properties, a tensile strength of 56 kg/cm2, an elongation of 270%, and a surface resistivity of 7 x 10-3 ohm/cm2.

Since the electromagnetic-shielding gasket 1 is covered with a uniformly thick aluminium layer 17 with a f low surface resistivity, the electronic components in the housing 3 are sufficiently shielded from externally generated electromagnetic waves, thus preventing electromagnetic radiation and noise from causing malfunctioning of the electronic components.

The base material of the body 15 of the electromagnetic- shielding gasket 1 is an elastomer such as a silicone rubber, thus providing elasticity and low electrical resistivity. By sealing the gap between the housing 3 and the lid 5, the electromagnetic- shielding gasket 1 securely seals against electromagnetic waves.

In this embodiment, the base material of the gasket body 15, silicone rubber, does not contain any conductive particles, unlike the related-art gasket.

Instead, the aluminium layer 17 is evaporated onto the surface of the gasket body 15, thus not affecting the elasticity of the gasket body 15. Consequently, when the lid 5 is closed, the housing 3 is securely sealed against external humidity and air. 20 Since the electromagnetic-shielding gasket 1 has a rectangular section and thus a simple configuration,-the cost of manufacturing a metallic mould for its manufacture is not expensive. As shown in Figure 3, an electromagnetic- shielding gasket 119 constituting the second embodiment is cylindrical in cross- section. A titanium layer 123 of about two microns in thickness is applied by an evaporation process on the surface of a gasket body 121 formed of silicone rubber. Since the titanium layer 123 is durable, this embodiment can be used even in a severe embodiment.

As shown in Figure 4, an electromagnetic-shielding gasket 225 constituting a third embodiment has a partcircular cross-section. An aluminium layer 229 of about three microns in thickness is applied by an evaporation process onto the surface of the gasket body 227 which is 6 formed of a silicone rubber. The electromagneticshielding gasket 225 has flat flanges 231 and 233 extending longitudinally along the gasket 225, which facilitate the mounting of the gasket 225 on the housing. The aluminium layer 229 applied by an evaporation process can be applied to or omitted from the inner periphery 227a of the gasket body 227.

An electromagnetic-shielding gasket 341 constituting a fourth embodiment is made of a sponge- like rubber. As shown in Figure 5, the electromagneticshielding gasket 341 is used, in the same way as the other embodiments, in the clearance between the housing 343 and its lid. The electromagnet ic- shielding gasket 341, which has an L-shaped cross-section, is placed on an upper end 347 of a side wall 345 of the housing 343.

The base material of the electromagnetic-shielding gasket 341 is preferably a flexible foamed elastomer. A gasket body 349 could be manufactured, for example, by blowing air into unvulcanised latex, or by adding a foaming agent such as sodium bicarbonate to a masticated elastomer. An aluminium layer 351 about four microns in thickness is applied by an evaporation process onto the surface of the gasket body 349. The electromagneticshielding gasket 341 of the fourth embodiment is elastic and impact resistant. The electromagnetic-shielding gasket 341 cap fit a clearance with a complicated configuration, and thus make the housing 343 watertight and airtight.

An electromagnetic-shielding gasket 453 constituting a fifth embodiment is also made of a sponge-like rubber. As shown in Figure 6, the electromagnetic-shielding gasket 453 has an inverted T-shaped cross-section, and has a nickel or copper layer 455 of about two microns in thickness applied by an evaporation process onto its surface.

Figure 7 shows an electromagnetic-shielding gasket 1 7 557 constituting a sixth embodiment. An aluminium layer 559 of about three microns in thickness is applied by an evaporation process onto the surface of a cylindrical sponge-rubber electromagnetic-shielding gasket 557.

The metallic membrane of two to four microns in thickness applied onto the surface of the electromagnetic-shielding body provides an electromagnet ic- shielding effect without affecting the elasticity of the body.

Although specific embodiments of the invention have been described for the purpose of illustration, the invention is not limited to the embodiments illustrated and described. For example, the electromagneticshielding material of this invention is not limited to the electromagneticshielding gasket made of silicone rubber or sponge rubber. Other kinds of elastomer and synthetic resin could be used. The configuration of this material could be tubular or columnar, and its cross-section could be circular, elliptical, part- circular shaped, T-shaped, or L-shaped. The conductive membrane formed on the surface of the body material could be aluminium, titanium, nickel, copper, or another metallic layer. Furthermore, this material could be used at any joint section between components.

8

Claims (10)

1. An electromagnetic-shielding gasket or sealing member for sealing gaps and for preventing electromagnetic waves from passing through the gaps, comprising a gasket or seal body formed of a synthetic elastomeric resin material. and a conductive membrane applied by an evaporation process onto a surface of the gasket or seal body.
2. An electromagnetic-shielding gasket or sealing member as claimed in claim 1, in which the gasket or seal body is formed of a silicone rubber.
is
3. An electromagnetic-shielding gasket or sealing member as claimed in claim 1, in which the gasket or seal body is formed of a sponge-like rubber.
4. An electromagnetic-shielding gasket or sealing member as claimed in any preceding claim, in which -the conductive membrane covers all exterior surfaces of the gasket or seal body.
5. An electromagnetic-shielding gasket or sealing member as claimed in any preceding claim, in which the conductive membrane is metallic.
6. An electromagnetic-shielding gasket or sealing member as claimed in claim 5, in which the conductive membrane comprises aluminium.
7. An electromagnetic-shielding gasket or sealing member as claimed in claim 5, in which the conductive membrane comprises titanium.
1 k 9 k
8. An electromagnetic-shielding gasket or sealing member as claimed in claim 5, in which the conductive membrane comprises nickel-copper alloy.
9. An electromagnetic-shielding gasket or sealing member substantially as hereinbefore described with reference to and as illustrated in the any of the accompanying drawings.
10. A housing for electronic components provided with a sealing gasket or sealing member as claimed in any preceding claim.
Published 1990 at The Patent C=co. State House. 867 t High Ho3burn. London VrC 1A 4TP Further copies may be obtained from The Patent Offloo. Silos Branch. St Mary Cray. Orpington. K2=18RS 3RD. Printed by Multiplex teebauques ltd, St Mary Cray. Kent, Con. L37 QWv - __Y ".Y. --m- - - -_,Y -V- _4_ -,.. __j
GB8921115A 1988-09-20 1989-09-18 Electromagnetic-shielding gasket or sealing member Expired - Fee Related GB2222913B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP23571588A JPH0282698A (en) 1988-09-20 1988-09-20 Electromagnetic wave shielding member

Publications (3)

Publication Number Publication Date
GB8921115D0 GB8921115D0 (en) 1989-11-01
GB2222913A true true GB2222913A (en) 1990-03-21
GB2222913B GB2222913B (en) 1992-08-26

Family

ID=16990155

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8921115A Expired - Fee Related GB2222913B (en) 1988-09-20 1989-09-18 Electromagnetic-shielding gasket or sealing member

Country Status (3)

Country Link
JP (1) JPH0282698A (en)
DE (2) DE3930377C2 (en)
GB (1) GB2222913B (en)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5068493A (en) * 1988-11-10 1991-11-26 Vanguard Products Corporation Dual elastomer gasket shield for electronic equipment
US5107070A (en) * 1988-11-10 1992-04-21 Vanguard Products Corporation Dual elastomer gasket for protection against magnetic interference
US5141770A (en) * 1988-11-10 1992-08-25 Vanguard Products Corporation Method of making dual elastomer gasket shield for electromagnetic shielding
GB2234861B (en) * 1988-11-10 1993-03-10 Vanguard Products Corp Dual elastomer gasket shield for electronic equipment
GB2224604B (en) * 1988-10-28 1993-04-21 Kitagawa Ind Co Ltd A conductive seal
US6410846B1 (en) 1998-12-15 2002-06-25 Vanguard Products Corporation Electromagnetic interference shielding device
US6608251B1 (en) 1999-06-24 2003-08-19 Nokia Corporation Protecting device against interfering electromagnetic radiation comprising EMI-gaskets
US6613976B1 (en) 1998-12-15 2003-09-02 Vanguard Products Corporation Electromagnetic interference shielding gasket
US6639145B1 (en) 1999-06-24 2003-10-28 Nokia Corporation Protecting device against interfering electromagnetic radiation comprising EMI gaskets
US6696639B1 (en) 1999-06-24 2004-02-24 Nokia Corporation Protecting device against interfering electromagnetic radiation comprising EMI-gaskets
US6714423B1 (en) 1999-06-24 2004-03-30 Nokia Corporation Protecting device against electromagnetic radiation comprising EMI-gaskets
US7345239B2 (en) * 2003-12-11 2008-03-18 Hewlett-Packard Development Company, L.P. System and method for routing cables

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE9014003U1 (en) * 1990-10-08 1990-12-13 Alfred Kunz Gmbh & Co, 8000 Muenchen, De
JP2563308Y2 (en) * 1991-03-25 1998-02-18 信越ポリマー株式会社 Electromagnetic shielding packing material
DE4333651A1 (en) * 1993-10-02 1995-04-06 Heidenhain Gmbh Dr Johannes A position
DE4343702C1 (en) * 1993-12-21 1995-03-09 Siemens Audiologische Technik Hearing aid worn on the head
DE19617656A1 (en) * 1996-05-03 1997-11-06 Siegfried Schaal Metallveredel Screening molding for electronic components
WO1998015162A1 (en) * 1996-10-04 1998-04-09 Ericsson Inc. Gasket for emi shielding and environmental sealing
DE19729435A1 (en) * 1997-07-09 1999-02-11 Siemens Ag Flat seal with protective conductor function
EP1158846B1 (en) * 1997-10-27 2004-03-31 Parker Hannifin Corporation Tubular gasket for improved environmental sealing and EMI shielding
US6075205A (en) * 1997-10-27 2000-06-13 Parker-Hannifin Corporation Tubular extrusion gasket profile exhibiting a controlled deflection response for improved environmental sealing and EMI shielding
EP1252805A1 (en) * 2000-01-24 2002-10-30 Amesbury Group, Inc. Methods for producing emi shielding gasket
DE10119440B4 (en) * 2001-04-20 2005-12-08 Rohde & Schwarz Gmbh & Co. Kg Laying device for a sealing cord
JP2002344187A (en) * 2001-05-17 2002-11-29 Nippon Mektron Ltd Method of manufacturing gasket of electronic equipment
DE10143418C1 (en) * 2001-09-05 2003-04-03 Rowo Coating Ges Fuer Beschich Material for shielding electromagnetic radiation and / or for making electrical contact with electrically conductive components
DE10230902A1 (en) * 2002-07-09 2004-02-05 Faist Systeme Gmbh Arrangement for protection against electromagnetic interference and electrostatic
DE10231145A1 (en) * 2002-07-10 2004-01-29 Siemens Ag Shielding for electronic components on a circuit board

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2098808A (en) * 1981-05-19 1982-11-24 Rfi Shielding Ltd Sealing gasket for radio interference suppression
GB2174551A (en) * 1985-03-28 1986-11-05 Rainford Metals Limited Screened rack
GB2194579A (en) * 1986-08-30 1988-03-09 Marconi Co Ltd Door seal

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE6607180U (en) * 1962-09-28 1971-01-28 Siemens Ag Electric geraet with shielding
JPS6127399B2 (en) * 1974-03-06 1986-06-25 Nikken Chemicals Co Ltd

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2098808A (en) * 1981-05-19 1982-11-24 Rfi Shielding Ltd Sealing gasket for radio interference suppression
GB2174551A (en) * 1985-03-28 1986-11-05 Rainford Metals Limited Screened rack
GB2194579A (en) * 1986-08-30 1988-03-09 Marconi Co Ltd Door seal

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2224604B (en) * 1988-10-28 1993-04-21 Kitagawa Ind Co Ltd A conductive seal
US5068493A (en) * 1988-11-10 1991-11-26 Vanguard Products Corporation Dual elastomer gasket shield for electronic equipment
US5107070A (en) * 1988-11-10 1992-04-21 Vanguard Products Corporation Dual elastomer gasket for protection against magnetic interference
US5141770A (en) * 1988-11-10 1992-08-25 Vanguard Products Corporation Method of making dual elastomer gasket shield for electromagnetic shielding
GB2234861B (en) * 1988-11-10 1993-03-10 Vanguard Products Corp Dual elastomer gasket shield for electronic equipment
US6410846B1 (en) 1998-12-15 2002-06-25 Vanguard Products Corporation Electromagnetic interference shielding device
US6613976B1 (en) 1998-12-15 2003-09-02 Vanguard Products Corporation Electromagnetic interference shielding gasket
US6608251B1 (en) 1999-06-24 2003-08-19 Nokia Corporation Protecting device against interfering electromagnetic radiation comprising EMI-gaskets
US6639145B1 (en) 1999-06-24 2003-10-28 Nokia Corporation Protecting device against interfering electromagnetic radiation comprising EMI gaskets
US6696639B1 (en) 1999-06-24 2004-02-24 Nokia Corporation Protecting device against interfering electromagnetic radiation comprising EMI-gaskets
US6714423B1 (en) 1999-06-24 2004-03-30 Nokia Corporation Protecting device against electromagnetic radiation comprising EMI-gaskets
US7345239B2 (en) * 2003-12-11 2008-03-18 Hewlett-Packard Development Company, L.P. System and method for routing cables

Also Published As

Publication number Publication date Type
GB8921115D0 (en) 1989-11-01 grant
JPH0282698A (en) 1990-03-23 application
DE8910862U1 (en) 1989-10-26 grant
DE3930377A1 (en) 1990-03-29 application
GB2222913B (en) 1992-08-26 grant
DE3930377C2 (en) 2001-10-18 grant

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20040918